High-voltage wires used for high-voltage lead wires of television receivers and other equipment are known, for example, from JP-B-51-8465, JP-B-U-56-55859, and JP-B-60-38805 (the term "JP-B" used herein means an examined Japanese patent publication, and the term "JP-B-U" used herein means an examined Japanese utility model publication).
JP-B-51-8465 discloses an insulated wire having fire retardancy and superior electric characteristics at a high temperature. This wire comprises a conductor having thereon a crosslinked insulation layer, and a protective coating layer provided on the insulation layer. The crosslinked insulation layer is mainly composed of polyethylene having a melting point of 105.degree. C. or higher. The protective coating layer is mainly composed of a terpolymer of ethylene, vinyl acetate, and vinyl chloride.
JP-B-U-56-55859 discloses a high-voltage lead wire for a television receiver. This wire has a three layer structure of polyethylene insulation provided on a conductor, a flame resistant layer of electron-beam-irradiated polyvinyl chloride on the polyethylene insulation, and a crosslinked polyethylene sheath provided further thereon.
JP-B-60-38805 discloses an insulated wire having an insulation layer mainly composed of polyethylene provided on a conductor, and a fire retardant protective coating layer provided further thereon.
As mentioned above, every conventional high-voltage insulated wire has an insulation layer mainly composed of polyethylene and a fire retardant protective coating layer provided further thereon.
Conventional high-voltage wires having the above-mentioned structure have a remarkably high initial breakdown voltage of approximately 300 KV. The breakdown voltage does, however, decrease significantly during use over the long term. This decrease in the breakdown voltage does not cause any problems under mild service conditions. Recently, however, modern television receivers have become multifunctional and the high-voltage wires in these receivers are subjected to severe electrical conditions. For example, a grounding wire and a high-voltage wire are frequently in close proximity where it is highly probable that the decrease of the breakdown voltage during long term use will cause severe electrical damage.